Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
h,w=map(int,input().split())
maplis=[input() for i in range(h)]

que=deque([(0,0,1)])
used={(0,0)}
bcount =sum(s.count("#") for s in maplis)


def check(x,y,c):
    if x<0 or x>w-1 or y<0 or y>h-1:
        return
    if maplis[y][x]=="#":
        return
    if  (x,y) in used:
        return
    que.append((x,y,c+1))
    used.add((x,y))

f=-1
while que:
    x,y,c=que.popleft()
    if x==w-1 and y==h-1:
        f=c
        break
    check(x-1,y,c)
    check(x+1,y,c)
    check(x,y-1,c)
    check(x,y+1,c)
print(f if f==-1 else(h*w-f-bcount))